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采用铜模喷铸方式进行了稀土元素添加AZ91镁合金非平衡凝固实验,对比研究了稀土元素种类(Re=Ce,Er)及含量(0.25%,0.5%,0.75%,1%,质量分数)对镁合金晶粒尺寸、基体成分及相结构的影响规律。结果表明,同等含量条件下,Ce元素在α-Mg中的固溶度更低,溶质富集程度更明显,易形成Al11Ce3高熔点化合物相,合金细化效果比Er更好。随Ce含量增加,晶粒尺寸不断减小,β-Mg17Al12共晶相数量减少,分布趋于弥散。当Ce含量大于0.75%时,出现明显的晶粒粗化现象。在此基础上,从形核和生长的角度对上述细化机理进行了合理解释,并利用差热分析实验进行了有效验证。
The rare earth elements (Re = Ce, Er) and their contents (0.25%, 0.5%, 0.75%, 1%, mass fraction) On magnesium alloy grain size, matrix composition and phase structure of the law. The results show that under the same content, the solubility of Ce in α-Mg is lower and the concentration of solute is more obvious. It is easy to form Al11Ce3 high melting point compound phase, and the refining effect of alloy is better than Er. With the increase of Ce content, the grain size decreases, the amount of β-Mg17Al12 eutectic phase decreases, the distribution tends to diffuse. When Ce content is more than 0.75%, obvious grain coarsening appears. On this basis, the above refinement mechanism is explained reasonably from the point of nucleation and growth, and the differential thermal analysis experiment is validated.